Is it worth having my lawn sprinker system professionally closed for winter?

Or is it something I could do myself just as well and save $100. I do not have a compressor, so I would be going without the powerflush, but I've heard from some people that it isn't necessary at all... any thoughts?

Is it worth having my lawn sprinker system professionally closed for winter?

Have a look at the articles in the link below, there's one on how to winterize the home system. Don't pay for it if you are capable to do yourself, and never go into winter without blowing it out, you will regret it. It is quick and easy to do.

You can do it yourself, but you really do need a compressor. Turn water off. Drain supply line from inside basement. Connect compressor. Do not blowout through the backflow preventor. Remove or plumb in downstream as the oil from some compressors will foul up rubber washers in your backflow. It is best to run at 40-50 psi as higher pressures will create heat and stress on your components. Run each zones for two minutes each, usually the control box has a station test function that will cycle the zones through once for two minutes. If you have any 12" spray heads you will want to push them down to empty their cases of water. Repeat until no more water comes out.

A properly designed and installed system would have a way to drain the water. If nothing else, a T with a valve (ball valve, spigot, whatever) at the end of the supply line that you leave closed during seasonal operation. A valve at the front also will help with bleeding the vacuum. At the end of the season, turn off the water and open the valve. No need for compressors, damaging backflows, etc. Just plain old gravity!